Flexible organic light emitting diode display having edge bending structure

ABSTRACT

The present disclosure relates to a flexible organic light emitting diode display having an edge bending structure. The organic light emitting diode display according to an embodiment includes a flexible plate including a display area, a non-display area surrounding the display area, and an edge bending area near the display area in the non-display area; a first line disposed in the non-display area on the flexible plate; a first buffer layer covering the first line; a second line on the first buffer layer in the non-display area; a second buffer layer covering the second line; gate elements disposed on the second buffer layer; an intermediate insulating layer covering the gate elements; data elements, and a connecting electrode connecting the first line to the second line on the intermediate insulating layer; and a plurality of trenches disposed at the edge bending area and penetrating the intermediate insulating layer, the second buffer layer and the first buffer layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korea Patent Application No.10-2015-0189675 filed on Dec. 30, 2015, which is incorporated herein byreference for all purposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure relates to a flexible flat panel display.Especially, the present disclosure relates to a flexible organic lightemitting diode display having edge bending structure.

Discussion of the Related Art

Nowadays, various flat panel display devices are developed forovercoming many drawbacks of the cathode ray tube such as heavy weightand bulk volume. The flat panel display devices include the liquidcrystal display device (or LCD), the field emission display (or FED),the plasma display panel (or PDP) and the electroluminescence device (orEL).

FIG. 1 is a plane view illustrating the structure of the organic lightemitting diode display having the active switching elements such as thethin film transistors according to the related art. FIG. 2 is a crosssectional view illustrating the structure of the organic light emittingdiode display along to the cutting line of I-I′ in FIG. 1 according tothe related art.

Referring to FIGS. 1 and 2, the organic light emitting diode displaycomprises a thin film transistor (or ‘TFT’) substrate having the thinfilm transistors ST and DT and an organic light emitting diode OLEconnected to and driven by the thin film transistors ST and DT, and abarrier film BF joining and facing the thin film transistor substratewith a sealant SE therebetween. The thin film transistor substrateincludes a switching thin film transistor ST, a driving thin filmtransistor DT connected to the switching thin film transistor ST, and anorganic light emitting diode OLE connected to the driving thin filmtransistor DT.

On a transparent substrate SUB, the switching thin film transistor ST isformed where a gate line GL and a data line DL are crossing each other.The switching thin film transistor ST acts for selecting the pixel whichis connected to the switching thin film transistor ST. The switchingthin film transistor ST includes a gate electrode SG branching from thegate line GL, a semiconductor channel layer SA overlapping with the gateelectrode SG a source electrode SS and a drain electrode SD. The drivingthin film transistor DT acts for driving an anode electrode ANO of theorganic light emitting diode OD disposed at the pixel selected by theswitching thin film transistor ST. The driving thin film transistor DTincludes a gate electrode DG connected to the drain electrode SD of theswitching thin film transistor ST, a semiconductor channel layer DA, asource electrode DS connected to the driving current line VDD, and adrain electrode DD. The drain electrode DD of the driving thin filmtransistor DT is connected to the anode electrode ANO of the organiclight emitting diode OLE.

As one example, FIG. 2 shows the thin film transistor of top gatestructure. In this case, the semiconductor channel layers SA and DA ofthe switching thin film transistor ST and the driving thin filmtransistor DT are firstly formed on the substrate SUB and the gateinsulating layer GI covers them and then the gate electrodes SG and DGare formed thereon by overlapping with the center portion of thesemiconductor channel layers SA and DA. After that, at both sides of thesemiconductor channel layers SA and DA, the source electrodes SS and DSand the drain electrodes SD and DD are connected thereto through contactholes penetrating an insulating layer IN. The source electrodes SS andDS and the drain electrodes SD and DD are formed on the insulating layerIN.

In addition, at the outer area of the substrate SUB surrounding thedisplay area where the pixel area is disposed, a gate pad GP formed atone end of the gate line GL, a data pad DP formed at one end of the dataline DL, and a driving current pad VDP formed at one end of the drivingcurrent line VDD are arrayed. As the gate pad GP is disposed at thedifferent layer from the data pad DP, some defects may occur at theoverlapping portion due to the level difference.

A passivation layer PAS is disposed to cover the upper entire surface ofthe substrate SUB having the switching and the driving thin filmtransistors ST and DT. After that, formed are the contact holes exposingthe gate pad GP, the data pad DP, the driving current pad VDP and thedrain electrode DD of the driving thin film transistor DD. Over thedisplay area within the substrate SUB, a planar layer PL is coated.Patterning the planar layer PL, a contact hole is formed for exposingthe drain electrode DD of the driving thin film transistor DT. Further,the planar layer PL is patterned as exposing the full areas of the padsat gate pad GP and the data pad DP. The planar layer PL makes theroughness of the upper surface of the substrate SUB in much smoothercondition, for coating the organic materials composing the organic lightemitting diode on the smooth and planar surface condition of thesubstrate SUB.

On the planar layer PL, the anode electrode ANO is formed to connect thedrain electrode DD of the driving thin film transistor DT through one ofthe contact holes. On the other hands, at the outer area of the displayarea not having the planar layer PL, formed are a gate pad electrodeGPT, a data pad electrode DPT and a driving current electrode VDPTconnected to the gate pad GP, the data pad DP and the driving currentpad VDP, respectively, exposed through the contact holes. On thesubstrate SUB, a bank BN is formed covering the display area, exceptingthe pixel area.

After completing the thin film transistor substrate, an inorganicmaterial such as the silicon nitride (SiNx) is deposited over the entiresurface of the substrate SUB with a thickness of 1˜3 μm for preventingthe organic light emitting diode from the invasion of the moisture oroxygen gas. Further, a sealant SE is disposed on the inner surface ofthe barrier film. It is preferable that the sealant SE has the boundarybeing apart with a predetermined distance from the edges of the barrierplate BF to the inside.

Aligning the barrier plate BF on the thin film transistor substrate, thebarrier plate BF is attached/joined with the thin film transistorsubstrate under pressure. After hardening the sealant SE between thebarrier film and the thin film transistor substrate, and then releasingthe pressure, the thin film transistor substrate has the surface sealingstructure by the barrier plate BF with the sealant SE. It is preferablethat the barrier plate BF is a film including plastic or organicmaterial.

It is preferable that the sealant SE and the barrier plate BF coversmost of all surface of the thin film substrate without the pad areabecause the pads would be connected to exterior devices. As exposed atoutside, the gate pad GP, the gate pad terminal GPT, the data pad GP andthe data pad terminal DPT would be connected to the exterior devicesthrough a connecting means.

According to the relative art, the organic light emitting diode displayis formed on a rigid substrate SUB. AS the substrate SUB having therigid property, it is proper to apply for the monitor, television set orportable display module. However, in the market, more various types ofthe display are required.

For example, the needs for the flexible display freely bendable orfoldable are increasing. Further, the needs for the non-bezel or thenarrow bezel display are also increasing, by bending or folding the nondisplay area (on which the display information is not shown) over thelateral sides or rear side. In order to develop these various styledisplays, it is required that the flexible display that the displayelements is formed on the flexible substrate.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned drawbacks, the purpose of thepresent disclosure is to suggest a flexible display in which the displayfunction is maintained even it is freely bend or folded. Another purposeof the present disclosure is to suggest a flexible display in which thenon-display area is moved behind the lateral side of the rear side bybending the boundary between the display area display area and thenon-display area. Still another purpose of the present disclosure is tosuggest a flexible display in which the display elements are not damagedby the bending stress occurred at the bending portions defined at theboundary of the display area and the non-display area.

In order to accomplish the above purpose, the present disclosuresuggests an organic light emitting diode display device comprising aflexible plate including a display area, a non-display area surroundingthe display area, and an edge bending area near the display area in thenon-display area; a first line disposed in the non-display area on theflexible plate; a first buffer layer covering the first line; a secondline on the first buffer layer in the non-display area; a second bufferlayer covering the second line; gate elements disposed on the secondbuffer layer; an intermediate insulating layer covering the gateelements; data elements, and a connecting electrode connecting the firstline to the second line on the intermediate insulating layer; and aplurality of trenches disposed at the edge bending area and penetratingthe intermediate insulating layer, the second buffer layer and the firstbuffer layer.

In one embodiment, the organic light emitting diode display devicefurther comprises a light shielding layer disposed at a same layer andincluding a same material with the first line in the display area; astorage electrode disposed at a same layer and including a same materialwith the second line in the display area; a switching thin filmtransistor and a driving thin film transistor connected to the switchingthin film transistor on the second buffer layer in the display area; andan organic light emitting diode connected to the driving thin filmtransistor.

In one embodiment, the gate elements includes a gate pad disposed in thenon-display area; a gate line extended from the gate pad over thedisplay area; and a gate electrode extruded from the gate line in thedisplay area, and the data elements includes: a data pad disposed in thenon-display area; a data line extended from the data pad over thedisplay area; a source electrode extruded from the data line in thedisplay area; a drain electrode facing with the source electrode; and agate pad terminal contacting the gate pad.

In one embodiment, the organic light emitting diode display devicefurther comprises a semiconductor layer overlapping with middle portionsof the gate electrode on the second buffer layer and under the gateelectrode; and a gate insulating layer covering entire surface of thesecond buffer layer between the semiconductor layer and the gateelectrode, wherein the trench penetrating the intermediate insulatinglayer, the gate insulating layer, the second buffer layer and the firstbuffer layer.

In some embodiments, the organic light emitting diode display devicefurther comprises a semiconductor layer overlapping with middle portionsof the gate electrode on the second buffer layer and under the gateelectrode; and a gate insulating layer having a same shape with the gateelectrode between the semiconductor layer and the gate electrode,wherein the trench penetrating the intermediate insulating layer, thesecond buffer layer and the first buffer layer.

In some embodiments, the organic light emitting diode display devicefurther comprises: an organic layer directly contacting entire of asurface of the flexible plate; a multi-buffer layer directly contactingentire of a surfaces of the organic layer; and a gate insulating layerdeposited on the multi-buffer layer, wherein the trench exposing some ofthe organic layer by penetrating the intermediate insulating layer, thegate insulating layer, the second buffer layer, the first buffer layerand the multi-buffer layer.

In some embodiments, the organic light emitting diode display devicefurther comprises an organic layer directly contacting entire of asurface of the flexible plate; and a multi-buffer layer directlycontacting entire of a surfaces of the organic layer, wherein the trenchexposing some of the organic layer by penetrating the intermediateinsulating layer, the second buffer layer, the first buffer layer andthe multi-buffer layer.

In some embodiments, the non-display area is disposed behind one of alateral side and a rear side of the display area by bending the edgebending area.

As the display elements are disposed on the flexible substrate, the flatpanel display according to the present disclosure maintains the displayfunction over all area normally, even though it is freely bent. Theflexible organic light emitting diode display includes the trenchesformed by eliminating some portions of the layers stacked at the bendingportions defined at the boundary between the display area and thenon-display area. Therefore, the bending stress can be reduced or weakenat the bending portions so that the elements are not damaged. As themost pad areas have the similar or same stack structure, the damages dueto the stack difference structure can be prevented. Further, as thetrenches can be formed by single etching process, the manufacturingprocess can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a plane view illustrating the structure of an organic lightemitting diode display having active switching elements such as thinfilm transistors according to the related art.

FIG. 2 is a cross sectional view illustrating the structure of theorganic light emitting diode display along the cutting line of I-I′ inFIG. 1 according to the related art.

FIG. 3 is a plane view illustrating a structure of a flexible organiclight emitting diode display having an edge bending structure accordingto the present disclosure.

FIGS. 4A and 4B are cross sectional views illustrating the structure ofa flexible organic light emitting diode display having an edge bendingstructure along the cutting line of II-II′ in FIG. 3, according to afirst embodiment of the present disclosure.

FIGS. 5A and 5B are cross sectional views illustrating the structure ofa flexible organic light emitting diode display having an edge bendingstructure along the cutting line of II-II′ in FIG. 3, according to asecond embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring to attached figures, preferred embodiments of the presentdisclosure will be explained. Like reference numerals designate likeelements throughout the detailed description. However, the presentdisclosure is not restricted by these embodiments but can be applied tovarious changes or modifications without changing the technical spirit.In the following embodiments, the names of the elements are selected byconsidering the easiness for explanation so that they may be differentfrom actual names.

First Embodiment

Referring to FIGS. 3, 4A and 4B, the first embodiment of the presentdisclosure will be explained. FIG. 3 is a plane view illustrating astructure of a flexible organic light emitting diode display having anedge bending structure according to the present disclosure. FIGS. 4A and4B are cross sectional views illustrating the structure of a flexibleorganic light emitting diode display having an edge bending structurealong the cutting line of II-II′ in FIG. 3, according to the firstembodiment of the present disclosure.

The flexible organic light emitting diode display according to the firstembodiment of the present disclosure comprises a thin film transistorsubstrate on which thin film transistors ST and DT and an organic lightemitting diode OLE driven by the thin film transistors ST and DT areformed. Further, a barrier plate attached on the thin film transistorsubstrate by a sealant may be included. The sealant and the barrierplate are not duplicately explained because they may be similar withthose of the related art.

The flexible organic light emitting diode display comprises a flexibleplate SUF not the rigid substrate and display elements disposed on theflexible plate SUF. The flexible plate SUF includes a display area AAand a non-display area NA. The display area AA is defined at the mostmiddle portions of the flexible plate SUF. The non-display area NAsurrounds the display area AA. For example, the non-display area NA maybe defined at the all four lateral sides of the flexible plate SUF, asfully surrounding the display area AA. Otherwise, only the upper sideand the left side of the flexible plate SUF are defined the non-displayareas NA. In some cases, any one side or parallel two sides may bedefined as the non-display area NA.

The non-display area NA includes pads GP and DP for receiving thesignals from the exterior devices. There are some dummy areas betweenthe pads GP and DP and the display area AA. These areas are alsoincluded into the non-display area NA, where the lines DL, VDD and GLare disposed. By bending the non-display area NA behind the rear side,the present disclosure suggests a display that only the display area isrecognized by the observer when seeing the display at just front side.Specifically, the pads GP and DP are bent over the rear side of thedisplay area AA.

To do so, the dummy area of the non-display area NA excluding the padsGP and DP would be easily bendable. This dummy area is defined as anedge bending area (or a bending portion) EBA. At the edge bending area,a plurality of the trenches TR are disposed for easy bending of theflexible plate SUF. The trench TR is formed where only the insulatinglayers among the various layers stacked on the flexible plate SUF aresequentially stacked. The trench TR has a well shape (or a sunken-downportion) by selectively removing some of the stacked insulating layers.

On the flexible plate SUF, the various layers are stacked and patterned,or various insulating layers are sequentially stacked. The stackedinsulating layers have different bending stress from the flexible plateSUF. Therefore, as the flexible display is bent repeatedly or it isseverely folded, the bending portions may be damaged due to thedifference of the stress. As a result, the insulating layers may be peeloff and the other layer disposed between the insulating layers may bedamaged. By forming a plurality of trenches TR exposing some surface ofthe flexible plate SUF by removing some of the insulating layers at theedge bending area EBA, the insulating layers can be prevented from beingdamaged by the stress difference when the bending stresses are applied.

Hereinafter, referring to FIGS. 4A and 4B, the structure of the flexibleorganic light emitting diode display according to the first embodimentwill be explained in detail. For the convenience of the manufacturingfor the flexible organic light emitting diode display, at first, theflexible organic light emitting diode display is formed on a rigidsubstrate SUB. After that, the rigid substrate SUB is dispatched fromthe flexible organic light emitting diode display. FIG. 4A is a crosssectional view illustrating a structure of the flexible organic lightemitting diode display formed on the rigid substrate.

On the entire surface (whole surface) of a rigid substrate SUB, asacrifice layer SL is deposited. The sacrifice layer SL includes anamorphous silicon (a-Si) material. On the entire surface of thesacrifice layer SL, an organic layer PI is disposed. The organic layerPI includes a polyimide material having superior property (orresistance) to the high temperature. On the entire surface of theorganic layer PI, a multi-buffer layer MB is disposed. The multi-bufferlayer MB includes a plurality of the insulating layers stackedsequentially. For example, the silicon oxide layers and the siliconnitride layers may be alternatively stacked. Otherwise, the organiclayer and the inorganic layer may be alternatively stacked.

On the entire surface of the multi-buffer layer MB, a light shieldinglayer LS is formed. It is preferable that the light shielding layer LSis selectively formed where the thin film transistor would be disposed.On the entire surface of the substrate SUB having the light shieldinglayer LS, a buffer layer BUF is disposed. On the buffer layer BUF asoverlapping with the light shielding layer LS, a switching thin filmtransistor ST and a driving thin film transistor DT are disposed.

On the buffer layer BUF, the switching semiconductor layer SA of theswitching thin film transistor ST and the driving semiconductor layer DAof the driving thin film transistor DT are firstly formed. On thesemiconductor layers SA and DA, a gate insulating layer GI is disposedas covering the entire surface of the substrate SUB. On the gateinsulating layer GI, gate electrodes SG and DG are formed as overlappingwith the semiconductor layers SA and DA, respectively. For example, theswitching gate electrode SG of the switching thin film transistor ST isoverlapped with the middle portions of the switching semiconductor layerSA. The driving gate electrode DG of the driving thin film transistor DTis overlapped with the middle portions of the driving semiconductorlayer DA.

On the entire surface of the substrate SUB having the gate electrodes SGand DG; an intermediate insulating layer ILD is disposed. On theintermediate insulating layer ILD, source-drain electrodes SS-DD andDS-DD are formed for completing the thin film transistors ST and DT. Forexample, the switching source electrode SS of the switching thin filmtransistor ST contacts one side of the switching semiconductor layer SAthrough a contact hole penetrating the intermediate insulating layer ILDand the gate insulating layer GI. The switching drain electrode SD ofthe switching thin film transistor ST contacts the other side of theswitching semiconductor layer SA through a contact hole penetrating theintermediate insulating layer ILD and the gate insulating layer GI. Thedriving thin film transistor DT has a driving source electrode DS and adriving drain electrode DD, like the switching thin film transistor ST.The switching drain electrode SD of the switching thin film transistorST connects to the driving gate electrode DG of the driving thin filmtransistor DT.

In the non-display area NA, a gate pad GP and a data pad DP aredisposed. The gate pad GP is disposed on the multi-buffer layer MB, thebuffer layer BUF and the gate insulating layer GI. On the contrary, thedata pad DP is disposed on the multi-buffer layer MB and theintermediate insulating layer ILD. The reason for that the gate pad GPhas the different stack structure from the data pad DP is that thetrenches TR are formed at the edge bending area EBA in the non-displayarea NA.

For example, the trench TR may have the structure for exposing theorganic layer PI. For this, when forming the gate electrodes SG and DG;the gate pad GP is formed at the same time. After depositing the gateinsulating layer GI, the trenches TR are formed by patterning the gateinsulating layer GI, the buffer layer BUF and the multi-buffer layer MB.At this time, at the non-display area where the data pad DP would bedisposed, all layers stacked on the organic layer PI are removed.

After that, the intermediate insulating layer ILD is deposited on theentire surface of the substrate SUB. When forming the source-drainelectrodes SS-SD and DS-DD on the intermediate insulating layer ILD, thedata line DL, the driving current line VDD and the data pad DP areformed. As the intermediate insulating layer ILD is remained under thedata pad DP, the intermediate insulating layer ILD is patterned to formthe trench TR. At that time, the intermediate insulating layer ILDcovering the gate pad GP is also removed.

On the entire surface of the substrate SUB having the source-drainelectrodes SS-SD and DS-Dd, a passivation layer PAS is deposited.Patterning the passivation layer PAS, the pads GP and DP are exposed andthe trenches TR are completed. After that, a planar layer PL isdeposited on the surface of the substrate SUB. It is preferable that theplanar layer PL covers within the display area AA.

By patterning the planar layer PL and the passivation layer PAS, thedriving drain electrode DD of the driving thin film transistor DT isexposed. By depositing a conductive material on the planar layer PL andpatterning it, an anode electrode ANO is formed as connecting to thedriving drain electrode DD of the driving thin film transistor DT.

By disposing a bank material on the planar layer PL having the anodeelectrode ANO, and patterning it, the emission area is defined on theanode electrode ANO. By depositing an organic light emitting layer OLand the cathode electrode CAT sequentially, an organic light emittingdiode OLE is formed.

The organic light emitting diode display as shown in FIG. 4A is stillnot the flexible organic light emitting diode display, because that thedisplay elements are not on the rigid substrate SUB. To complete theflexible organic light emitting diode display, the sacrifice layer SLshould be removed by radiating a laser focusing on the sacrifice layerSL. As a result, the rigid substrate SUB is separated from the organiclayer PI. After that, a flexible film or a flexible plate SUF isattached on the bottom surface of the organic layer PI. Then, as shownin FIG. 4B, the flexible organic light emitting diode display iscompleted.

The flexible organic light emitting diode display according to the firstembodiment of the present disclosure includes a plurality of thetrenches TR at some area in the non-display area where the lines are notdisposed. The trenches TR have the well shape by removing the bufferlayers and the insulating layers over the organic layer PI. Bending theedge bending area EBA having the trenches TR, the pads GP and DP can bedisposed behind the rear side of the flexible plate SUF.

In the first embodiment, a plurality of trenches TR are disposed for theeasiness of the edge bending structure. In the first embodiment, themanufacturing process for the trenches TR has the 2˜3 mask processes.Therefore, the stack structure of the gate pad GP is different from thatof the data pad DP. In this case, the bending stress may still beremained at the edge bending area EBA due to the thick difference. Thismay cause defects at the elements for the display.

Second Embodiment

Hereinafter, referring to FIGS. 3, 5A and 5B the second embodiment willbe explained. The second embodiment suggests a structure of the flexibleorganic light emitting diode display in which the defects which may bepossibly associated with the first embodiment can be overcome oraddressed. Some of the main features of the second embodiment are easilyshown in the cross sectional view. Therefore, the structure in the planeview which is the same with the first embodiment will not be duplicated,and FIG. 3 is commonly used for the plane view. FIGS. 5A and 5B arecross sectional views illustrating a structure of a flexible organiclight emitting diode display having an edge bending structure along thecutting line of II-IF in FIG. 3, according to the second embodiment ofthe present disclosure.

For the flexible organic light emitting diode display according to thesecond embodiment of the present disclosure, at first, the displayelements are formed on a rigid substrate SUB, as shown in FIG. 5A. Afterthat, the rigid substrate SUB is dispatched from the display elements tocomplete the flexible organic light emitting diode display as shown inFIG. 5B.

Referring to FIG. 5A, on the entire surface of a rigid substrate SUB, asacrifice layer SL is deposited. On the entire surface of the sacrificelayer SL, an organic layer PI is disposed. The organic layer PI includesa polyimide film having superior property (or resistance) to the hightemperature.

On the entire surface of the organic layer PI, a multi-buffer layer MBis disposed. The multi-buffer layer MB includes a plurality of theinorganic insulating layers stacked sequentially. For example, thesilicon oxide layers and the silicon nitride layers may be alternativelystacked. Otherwise, the organic layer and the inorganic layer may bealternatively stacked. The multi-buffer layer MB is for preventing themoisture or gases from intruding into the display elements disposedthereon.

On the entire surface of the multi-buffer layer MB, a light shieldinglayer BS is formed. It is preferable that the light shielding layer BSis selectively formed where the thin film transistor would be disposed.Including an opaque metal material, the light shielding layer BS is alsoused for forming an additional storage. Further, disposing in thenon-display area NA, the light shielding layer BS is used for a linkerfor linking the pad to the line, in the non-display area. For example, aplurality of the connecting electrodes CN for linking the lines disposedon the different layers may be disposed in the non-display area NA.Using the opaque metal material for the light shielding layer BS is alsoused for a first line L1 linking to the connecting electrode CN.

On the light shielding layer BS, a first buffer layer BF1 is depositedas covering the entire surface of the substrate SUB. The first bufferlayer BF1 is for physically and electrically isolating the lightshielding layer BS from other conductive layer. Further, the firstbuffer layer BF1 is used for making the top surface of the substrate SUBin a smooth plane. On the first buffer layer BF1, a storage electrode BCis formed.

It is preferable that the storage electrode BC is disposed asoverlapping with the light shielding layer BS. That is, at the portionsof the first buffer layer BF1 between the light shielding layer BS andthe storage electrode BC, the additional storage is formed. To completethe additional storage, the light shielding layer BS may be connected tothe switching source electrode SS of the switching thin film transistorST, and the storage electrode BC may be connected to the driving gateelectrode DG of the driving thin film transistor DT.

In addition, disposed in the non-display area AA, the material of thestorage electrode BC is also used for a linker for linking the line andthe pad. For example, a plurality of the connecting electrodes CN forlinking the lines on the different layers may be disposed in thenon-display area NA. Using the opaque metal material for the storageelectrode BC is also used for a second line L2 linking to the connectingelectrode CN.

On the storage electrode BC, a second buffer layer BF2 is deposited ascovering the entire surface of the substrate SUB. The second bufferlayer BF2 is for physically and electrically isolating the storageelectrode BC from other conductive layer. On the second buffer layerBF2, a switching thin film transistor ST and a driving thin filmtransistor DT are formed.

On the second buffer layer BF2, a switching semiconductor layer SA ofthe switching thin film transistor ST and a driving semiconductor layerDA of the driving thin film transistor DT are disposed. On thesemiconductor layers SA and DA, a gate insulating layer GI is disposed.On the gate insulating layer GI, the gate elements are formed. The gateelements include a gate line GL, gate electrodes SG and DG and a gatepad GP. In the case that the driving gate electrode DG is connected tothe storage electrode BC, before forming the gate elements, some of thestorage electrode BC is exposed by patterning the gate insulating layerGI and the second buffer layer BF2.

The switching gate electrode SG of the switching thin film transistor STis overlapping with the middle portions of the switching semiconductorlayer SA having the gate insulating layer therebetween. The driving gateelectrode DG of the driving thin film transistor DT is overlapping withthe middle portions of the driving semiconductor layer DA having thegate insulating layer therebetween. The gate line GL is connected to theswitching gate electrode SG of the switching thin film transistor ST.The gate pad GP is disposed at one end of the gate line GL. The gatesignal applied to the gate pad GP is supplied to the switching gateelectrode SG of the switching thin film transistor ST through the gateline GL.

On the gate elements, an intermediate insulating layer ILD is disposedas covering the entire surface of the substrate SUB. The intermediateinsulating layer ILD is for isolating the gate elements from the otherconductive layer disposed at the other layer physically andelectrically. On the intermediate insulating layer ILD, the dataelements are formed. Some of data elements may be connected to otherelements disposed under the intermediate insulating layer ILD. Bypatterning the intermediate insulating layer ILD and the gate insulatinglayer GI, the contact holes are formed. For example, both sides of thesemiconductor layers SA and DA are exposed. At the same time, thedriving gate electrode DG of the driving thin film transistor DT isexposed. Further, the gate pad GP is exposed.

When patterning the intermediate insulating layer ILD and/or the gateinsulating layer GI, at the non-display area NA, some portions of thefirst line L1 including the same material with the light shielding layerBS and some portions of the second line L2 including the same materialwith the storage electrode BC may be exposed. These contact holes arefor connecting the first line L1 to the second line L2, lately.

On the intermediate insulating layer ILD having the contact holes, bydepositing a metal material and patterning it, the data elements areformed. The data elements include a switching source electrode SS and aswitching drain electrode SD of the switching thin film transistor ST, adriving source electrode DS and a driving drain electrode DD of thedriving thin film transistor DT, a data line DL, a data pad DP, adriving current line VDD and a driving pad VDP.

The switching source electrode SS of the switching thin film transistorST contacts one side of the switching semiconductor layer SA and theswitching drain electrode SD contacts the other side of the switchingsemiconductor layer SA. The switching drain electrode SD is connected tothe driving gate electrode DG. The data line DL is connected to theswitching source electrode SS of the switching thin film transistor ST.The data pad DP is disposed at one end of the data line DL. The drivingsource electrode DS of the driving thin film transistor DT contacts oneside of the driving semiconductor layer DA and the driving drainelectrode DD contacts the other side of the driving semiconductor layerDA. The driving current line VDD is connected to the driving sourceelectrode DS of the driving thin film transistor DT. The driving pad VDPis disposed at one end of the driving current line VDD.

In some cases, the switching source electrode SS is connected to thelight shielding layer BS. In the case that the storage electrode BCoverlapping with the light shielding layer BS is connected to thedriving gate electrode DG the additional storage capacitance is formedbetween the light shielding layer BS and the storage electrode BC.

In the non-display area NA, the data pad DP at the one end of the dataline DL and the driving pad VDP at the one end of the driving currentline VDD are disposed. The data elements further include a gate padterminal GPT contacting the gate pad GP. Further, the data elementsinclude the connecting electrodes CN in the non-display area NA. Theconnecting electrode CN connects the first line L1 made of the samematerial with the light shielding layer BS and the second line L2 madeof the same material with the storage electrode BC, via the contacthole.

On the entire surface of the substrate SUB having the data elements, apassivation layer PAS is deposited. Patterning the passivation layerPAS, some portions of the date elements are exposed. At the same time, aplurality of trenches TR are formed. For example, in the non-displayarea NA, the passivation layer PAS is patterned to expose some portionsof the data elements. By etching the passivation layer PAS, theintermediate insulating layer ILD, the gate insulating layer GI, thesecond buffer layer BF2, the first buffer layer BF1 and the multi-bufferlayer MB sequentially, the trenches TR may be formed. It is preferablethat the trenches TR are disposed at the edge bending area EBA in thenon-display area NA. For example, the trenches TR may be disposed wherethere are no lines GL and DL between the pad area GP and DP and thedisplay area AA.

After that, a planar layer PL is deposited on the surface of thesubstrate SUB. It is preferable that the planar layer PL covers withinthe display area AA. Patterning the planar layer PL and the passivationlayer PAS, the driving drain electrode DD of the driving thin filmtransistor DT is exposed. By depositing a conductive material on theplanar layer PL and patterning it, an anode electrode ANO is formed asconnecting to the driving drain electrode DD of the driving thin filmtransistor DT.

By disposing a bank material on the planar layer PL having the anodeelectrode ANO, and patterning it, the emission area is defined on theanode electrode ANO. By depositing an organic light emitting layer OLand the cathode electrode CAT sequentially, an organic light emittingdiode OLE is formed.

The organic light emitting diode display as shown in FIG. 5A is stillnot the flexible organic light emitting diode display, because that thedisplay elements are not on the rigid substrate SUB. To complete theflexible organic light emitting diode display, the sacrifice layer SLshould be removed by radiating a laser focusing on the sacrifice layerSL. As a result, the rigid substrate SUB is separated from the organiclayer PI. After that, a flexible film or a flexible plate SUF isattached on the bottom surface of the organic layer PI. Then, as shownin FIG. 5B, the flexible organic light emitting diode display iscompleted.

In the second embodiment of the present disclosure, using the metallayers used for the light shielding layer BS and the storage electrodeBC in the display area AA, the first line L1 and the second line L2 areformed in the non-display area AA. Using the first line L1 and thesecond line L2, one of the gate elements and one of the data elementsare connected each other. In the second embodiment, the gate elementsand the data elements have the same stack structure in the non-displayarea NA.

By selectively removing the stacked insulating layers in the non-displayarea NA, the trenches TR are formed. The trenches TR are disposed at theedge bending area EBA when the non-display area NA is bent to the rearside of the display area AA. The bending stress may be concentrated atthe edge bending area EBA. In the case that various elements aredisposed at the edge bending area EBA, they may be easily damaged asbending the non-display area NA. According to the second embodiment,with the trenches TR disposed at the edge bending area EBA, the bendingstress can be scattered or reduced. As a result, the damages caused atthe edge bending area EBA can be prevented.

Further, as the stack structures of the entire pad area are similar orsame, the damages caused by shape difference or level difference can beprevented. In addition, as the trenches TR can be formed by singleetching process, the manufacturing process can be minimized.

Until now, the flexible organic light emitting diode display in whichthe thin film transistors have the top gate structure is explained.However, one or more of the main ideas of the present disclosure can beapplied to the organic light emitting diode display having the bottomgate structure thin film transistors. Further, the switching thin filmtransistor may have the different type from the driving thin filmtransistor. For example, the switching thin film transistor has the topgate structure, but the driving thin film transistor has the bottom gatestructure, or vice versa.

In the above explanations, the gate insulating layer GI covers theentire surface of the substrate on the semiconductor layer. However, thegate insulating layer GI may be patterned with the gate electrode. Inthat case, the gate insulating layer GI has the same shape with the gateelectrode, and disposed on the middle portions of the semiconductorlayer overlapping with the gate electrode. In that case, the trenchesmay have the well structure in which the organic layer is exposed byetching to penetrate the intermediate insulating layer, the secondbuffer layer, the first buffer layer and the multi-buffer layer.

While the embodiments of the present invention have been described indetail with reference to the drawings, it will be understood by thoseskilled in the art that the invention can be implemented in otherspecific forms without changing the technical spirit or essentialfeatures of the invention. Therefore, it should be noted that theforgoing embodiments are merely illustrative in all aspects and are notto be construed as limiting the invention. The scope of the invention isdefined by the appended claims rather than the detailed description ofthe invention. All changes or modifications or their equivalents madewithin the meanings and scope of the claims should be construed asfalling within the scope of the invention.

What is claimed is:
 1. A flexible organic light emitting diode displaydevice comprising: a flexible plate including a display area, anon-display area surrounding the display area, and an edge bending areanear the display area in the non-display area; a first line disposed inthe non-display area on the flexible plate; a first buffer layercovering the first line; a second line on the first buffer layer in thenon-display area; a second buffer layer covering the second line; gateelements disposed on the second buffer layer; an intermediate insulatinglayer covering the gate elements; data elements, and a connectingelectrode connecting the first line to the second line on theintermediate insulating layer; and a plurality of trenches disposed atthe edge bending area and penetrating the intermediate insulating layer,the second buffer layer and the first buffer layer.
 2. The flexibleorganic light emitting diode display device according to claim 1,further comprising: a light shielding layer disposed at a same layer andincluding a same material with the first line in the display area; astorage electrode disposed at a same layer and including a same materialwith the second line in the display area; a switching thin filmtransistor and a driving thin film transistor connected to the switchingthin film transistor on the second buffer layer in the display area; andan organic light emitting diode connected to the driving thin filmtransistor.
 3. The flexible organic light emitting diode display deviceaccording to claim 1, wherein the gate elements includes: a gate paddisposed in the non-display area; a gate line extended from the gate padover the display area; and a gate electrode extruded from the gate linein the display area, and wherein the data elements includes: a data paddisposed in the non-display area; a data line extended from the data padover the display area; a source electrode extruded from the data line inthe display area; a drain electrode facing with the source electrode;and a gate pad terminal contacting the gate pad.
 4. The flexible organiclight emitting diode display device according to claim 3, furthercomprising: a semiconductor layer overlapping with middle portions ofthe gate electrode on the second buffer layer and under the gateelectrode; and a gate insulating layer covering an entire surface of thesecond buffer layer between the semiconductor layer and the gateelectrode, wherein the trench penetrates the intermediate insulatinglayer, the gate insulating layer, the second buffer layer and the firstbuffer layer.
 5. The flexible organic light emitting diode displaydevice according to claim 3, further comprising: a semiconductor layeroverlapping with middle portions of the gate electrode on the secondbuffer layer and under the gate electrode; and a gate insulating layerhaving a same shape with the gate electrode between the semiconductorlayer and the gate electrode, wherein the trench penetrates theintermediate insulating layer, the second buffer layer and the firstbuffer layer.
 6. The flexible organic light emitting diode displaydevice according to claim 1, further comprising: an organic layerdirectly contacting an entire surface of the flexible plate; amulti-buffer layer directly contacting an entire surface of the organiclayer; and a gate insulating layer deposited on the multi-buffer layer,wherein the trench exposes some of the organic layer by penetrating theintermediate insulating layer, the gate insulating layer, the secondbuffer layer, the first buffer layer and the multi-buffer layer.
 7. Theflexible organic light emitting diode display device according to claim1, further comprising: an organic layer directly contacting an entiresurface of the flexible plate; and a multi-buffer layer directlycontacting an entire surface of the organic layer, wherein the trenchexposes some of the organic layer by penetrating the intermediateinsulating layer, the second buffer layer, the first buffer layer andthe multi-buffer layer.
 8. The flexible organic light emitting diodedisplay device according to claim 1, wherein the non-display area isdisposed behind one of a lateral side and a rear side of the displayarea by bending the edge bending area.